/**
* DD_belatedPNG: Adds IE6 support: PNG images for CSS background-image and HTML <IMG/>.
* Author: Drew Diller
* Email: drew.diller@gmail.com
* URL: http://www.dillerdesign.com/experiment/DD_belatedPNG/
* Version: 0.0.8a
* Licensed under the MIT License: http://dillerdesign.com/experiment/DD_belatedPNG/#license
*
* Example usage:
* DD_belatedPNG.fix('.png_bg'); // argument is a CSS selector
* DD_belatedPNG.fixPng( someNode ); // argument is an HTMLDomElement
* <!--[if IE 6]><script src="js/png24.js"></script><script>DD_belatedPNG.fix('*');</script><![endif]-->
**/

/*
PLEASE READ:
Absolutely everything in this script is SILLY.  I know this.  IE's rendering of certain pixels doesn't make sense, so neither does this code!
*/

var DD_belatedPNG = {
  ns: 'DD_belatedPNG',
  imgSize: {},
  delay: 10,
  nodesFixed: 0,
  createVmlNameSpace: function () { /* enable VML */
    if (document.namespaces && !document.namespaces[this.ns]) {
      document.namespaces.add(this.ns, 'urn:schemas-microsoft-com:vml');
    }
  },
  createVmlStyleSheet: function () { /* style VML, enable behaviors */
    /*
      Just in case lots of other developers have added
      lots of other stylesheets using document.createStyleSheet
      and hit the 31-limit mark, let's not use that method!
      further reading: http://msdn.microsoft.com/en-us/library/ms531194(VS.85).aspx
    */
    var screenStyleSheet, printStyleSheet;
    screenStyleSheet = document.createElement('style');
    screenStyleSheet.setAttribute('media', 'screen');
    document.documentElement.firstChild.insertBefore(screenStyleSheet, document.documentElement.firstChild.firstChild);
    if (screenStyleSheet.styleSheet) {
      screenStyleSheet = screenStyleSheet.styleSheet;
      screenStyleSheet.addRule(this.ns + '\\:*', '{behavior:url(#default#VML)}');
      screenStyleSheet.addRule(this.ns + '\\:shape', 'position:absolute;');
      screenStyleSheet.addRule('img.' + this.ns + '_sizeFinder', 'behavior:none; border:none; position:absolute; z-index:-1; top:-10000px; visibility:hidden;'); /* large negative top value for avoiding vertical scrollbars for large images, suggested by James O'Brien, http://www.thanatopsic.org/hendrik/ */
      this.screenStyleSheet = screenStyleSheet;
      
      /* Add a print-media stylesheet, for preventing VML artifacts from showing up in print (including preview). */
      /* Thanks to R閙i Pr関ost for automating this! */
      printStyleSheet = document.createElement('style');
      printStyleSheet.setAttribute('media', 'print');
      document.documentElement.firstChild.insertBefore(printStyleSheet, document.documentElement.firstChild.firstChild);
      printStyleSheet = printStyleSheet.styleSheet;
      printStyleSheet.addRule(this.ns + '\\:*', '{display: none !important;}');
      printStyleSheet.addRule('img.' + this.ns + '_sizeFinder', '{display: none !important;}');
    }
  },
  readPropertyChange: function () {
    var el, display, v;
    el = event.srcElement;
    if (!el.vmlInitiated) {
      return;
    }
    if (event.propertyName.search('background') != -1 || event.propertyName.search('border') != -1) {
      DD_belatedPNG.applyVML(el);
    }
    if (event.propertyName == 'style.display') {
      display = (el.currentStyle.display == 'none') ? 'none' : 'block';
      for (v in el.vml) {
        if (el.vml.hasOwnProperty(v)) {
          el.vml[v].shape.style.display = display;
        }
      }
    }
    if (event.propertyName.search('filter') != -1) {
      DD_belatedPNG.vmlOpacity(el);
    }
  },
  vmlOpacity: function (el) {
    if (el.currentStyle.filter.search('lpha') != -1) {
      var trans = el.currentStyle.filter;
      trans = parseInt(trans.substring(trans.lastIndexOf('=')+1, trans.lastIndexOf(')')), 10)/100;
      el.vml.color.shape.style.filter = el.currentStyle.filter; /* complete guesswork */
      el.vml.image.fill.opacity = trans; /* complete guesswork */
    }
  },
  handlePseudoHover: function (el) {
    setTimeout(function () { /* wouldn't work as intended without setTimeout */
      DD_belatedPNG.applyVML(el);
    }, 1);
  },
  /**
  * This is the method to use in a document.
  * @param {String} selector - REQUIRED - a CSS selector, such as '#doc .container'
  **/
  fix: function (selector) {
    if (this.screenStyleSheet) {
      var selectors, i;
      selectors = selector.split(','); /* multiple selectors supported, no need for multiple calls to this anymore */
      for (i=0; i<selectors.length; i++) {
        this.screenStyleSheet.addRule(selectors[i], 'behavior:expression(DD_belatedPNG.fixPng(this))'); /* seems to execute the function without adding it to the stylesheet - interesting... */
      }
    }
  },
  applyVML: function (el) {
    el.runtimeStyle.cssText = '';
    this.vmlFill(el);
    this.vmlOffsets(el);
    this.vmlOpacity(el);
    if (el.isImg) {
      this.copyImageBorders(el);
    }
  },
  attachHandlers: function (el) {
    var self, handlers, handler, moreForAs, a, h;
    self = this;
    handlers = {resize: 'vmlOffsets', move: 'vmlOffsets'};
    if (el.nodeName == 'A') {
      moreForAs = {mouseleave: 'handlePseudoHover', mouseenter: 'handlePseudoHover', focus: 'handlePseudoHover', blur: 'handlePseudoHover'};
      for (a in moreForAs) {      
        if (moreForAs.hasOwnProperty(a)) {
          handlers[a] = moreForAs[a];
        }
      }
    }
    for (h in handlers) {
      if (handlers.hasOwnProperty(h)) {
        handler = function () {
          self[handlers[h]](el);
        };
        el.attachEvent('on' + h, handler);
      }
    }
    el.attachEvent('onpropertychange', this.readPropertyChange);
  },
  giveLayout: function (el) {
    el.style.zoom = 1;
    if (el.currentStyle.position == 'static') {
      el.style.position = 'relative';
    }
  },
  copyImageBorders: function (el) {
    var styles, s;
    styles = {'borderStyle':true, 'borderWidth':true, 'borderColor':true};
    for (s in styles) {
      if (styles.hasOwnProperty(s)) {
        el.vml.color.shape.style[s] = el.currentStyle[s];
      }
    }
  },
  vmlFill: function (el) {
    if (!el.currentStyle) {
      return;
    } else {
      var elStyle, noImg, lib, v, img, imgLoaded;
      elStyle = el.currentStyle;
    }
    for (v in el.vml) {
      if (el.vml.hasOwnProperty(v)) {
        el.vml[v].shape.style.zIndex = elStyle.zIndex;
      }
    }
    el.runtimeStyle.backgroundColor = '';
    el.runtimeStyle.backgroundImage = '';
    noImg = true;
    if (elStyle.backgroundImage != 'none' || el.isImg) {
      if (!el.isImg) {
        el.vmlBg = elStyle.backgroundImage;
        el.vmlBg = el.vmlBg.substr(5, el.vmlBg.lastIndexOf('")')-5);
      }
      else {
        el.vmlBg = el.src;
      }
      lib = this;
      if (!lib.imgSize[el.vmlBg]) { /* determine size of loaded image */
        img = document.createElement('img');
        lib.imgSize[el.vmlBg] = img;
        img.className = lib.ns + '_sizeFinder';
        img.runtimeStyle.cssText = 'behavior:none; position:absolute; left:-10000px; top:-10000px; border:none; margin:0; padding:0;'; /* make sure to set behavior to none to prevent accidental matching of the helper elements! */
        imgLoaded = function () {
          this.width = this.offsetWidth; /* weird cache-busting requirement! */
          this.height = this.offsetHeight;
          lib.vmlOffsets(el);
        };
        img.attachEvent('onload', imgLoaded);
        img.src = el.vmlBg;
        img.removeAttribute('width');
        img.removeAttribute('height');
        document.body.insertBefore(img, document.body.firstChild);
      }
      el.vml.image.fill.src = el.vmlBg;
      noImg = false;
    }
    el.vml.image.fill.on = !noImg;
    el.vml.image.fill.color = 'none';
    el.vml.color.shape.style.backgroundColor = elStyle.backgroundColor;
    el.runtimeStyle.backgroundImage = 'none';
    el.runtimeStyle.backgroundColor = 'transparent';
  },
  /* IE can't figure out what do when the offsetLeft and the clientLeft add up to 1, and the VML ends up getting fuzzy... so we have to push/enlarge things by 1 pixel and then clip off the excess */
  vmlOffsets: function (el) {
    var thisStyle, size, fudge, makeVisible, bg, bgR, dC, altC, b, c, v;
    thisStyle = el.currentStyle;
    size = {'W':el.clientWidth+1, 'H':el.clientHeight+1, 'w':this.imgSize[el.vmlBg].width, 'h':this.imgSize[el.vmlBg].height, 'L':el.offsetLeft, 'T':el.offsetTop, 'bLW':el.clientLeft, 'bTW':el.clientTop};
    fudge = (size.L + size.bLW == 1) ? 1 : 0;
    /* vml shape, left, top, width, height, origin */
    makeVisible = function (vml, l, t, w, h, o) {
      vml.coordsize = w+','+h;
      vml.coordorigin = o+','+o;
      vml.path = 'm0,0l'+w+',0l'+w+','+h+'l0,'+h+' xe';
      vml.style.width = w + 'px';
      vml.style.height = h + 'px';
      vml.style.left = l + 'px';
      vml.style.top = t + 'px';
    };
    makeVisible(el.vml.color.shape, (size.L + (el.isImg ? 0 : size.bLW)), (size.T + (el.isImg ? 0 : size.bTW)), (size.W-1), (size.H-1), 0);
    makeVisible(el.vml.image.shape, (size.L + size.bLW), (size.T + size.bTW), (size.W), (size.H), 1 );
    bg = {'X':0, 'Y':0};
    if (el.isImg) {
      bg.X = parseInt(thisStyle.paddingLeft, 10) + 1;
      bg.Y = parseInt(thisStyle.paddingTop, 10) + 1;
    }
    else {
      for (b in bg) {
        if (bg.hasOwnProperty(b)) {
          this.figurePercentage(bg, size, b, thisStyle['backgroundPosition'+b]);
        }
      }
    }
    el.vml.image.fill.position = (bg.X/size.W) + ',' + (bg.Y/size.H);
    bgR = thisStyle.backgroundRepeat;
    dC = {'T':1, 'R':size.W+fudge, 'B':size.H, 'L':1+fudge}; /* these are defaults for repeat of any kind */
    altC = { 'X': {'b1': 'L', 'b2': 'R', 'd': 'W'}, 'Y': {'b1': 'T', 'b2': 'B', 'd': 'H'} };
    if (bgR != 'repeat' || el.isImg) {
      c = {'T':(bg.Y), 'R':(bg.X+size.w), 'B':(bg.Y+size.h), 'L':(bg.X)}; /* these are defaults for no-repeat - clips down to the image location */
      if (bgR.search('repeat-') != -1) { /* now let's revert to dC for repeat-x or repeat-y */
        v = bgR.split('repeat-')[1].toUpperCase();
        c[altC[v].b1] = 1;
        c[altC[v].b2] = size[altC[v].d];
      }
      if (c.B > size.H) {
        c.B = size.H;
      }
      el.vml.image.shape.style.clip = 'rect('+c.T+'px '+(c.R+fudge)+'px '+c.B+'px '+(c.L+fudge)+'px)';
    }
    else {
      el.vml.image.shape.style.clip = 'rect('+dC.T+'px '+dC.R+'px '+dC.B+'px '+dC.L+'px)';
    }
  },
  figurePercentage: function (bg, size, axis, position) {
    var horizontal, fraction;
    fraction = true;
    horizontal = (axis == 'X');
    switch(position) {
      case 'left':
      case 'top':
        bg[axis] = 0;
        break;
      case 'center':
        bg[axis] = 0.5;
        break;
      case 'right':
      case 'bottom':
        bg[axis] = 1;
        break;
      default:
        if (position.search('%') != -1) {
          bg[axis] = parseInt(position, 10) / 100;
        }
        else {
          fraction = false;
        }
    }
    bg[axis] = Math.ceil(  fraction ? ( (size[horizontal?'W': 'H'] * bg[axis]) - (size[horizontal?'w': 'h'] * bg[axis]) ) : parseInt(position, 10)  );
    if (bg[axis] % 2 === 0) {
      bg[axis]++;
    }
    return bg[axis];
  },
  fixPng: function (el) {
    el.style.behavior = 'none';
    var lib, els, nodeStr, v, e;
    if (el.nodeName == 'BODY' || el.nodeName == 'TD' || el.nodeName == 'TR') { /* elements not supported yet */
      return;
    }
    el.isImg = false;
    if (el.nodeName == 'IMG') {
      if(el.src.toLowerCase().search(/\.png$/) != -1) {
        el.isImg = true;
        el.style.visibility = 'hidden';
      }
      else {
        return;
      }
    }
    else if (el.currentStyle.backgroundImage.toLowerCase().search('.png') == -1) {
      return;
    }
    lib = DD_belatedPNG;
    el.vml = {color: {}, image: {}};
    els = {shape: {}, fill: {}};
    for (v in el.vml) {
      if (el.vml.hasOwnProperty(v)) {
        for (e in els) {
          if (els.hasOwnProperty(e)) {
            nodeStr = lib.ns + ':' + e;
            el.vml[v][e] = document.createElement(nodeStr);
          }
        }
        el.vml[v].shape.stroked = false;
        el.vml[v].shape.appendChild(el.vml[v].fill);
        el.parentNode.insertBefore(el.vml[v].shape, el);
      }
    }
    el.vml.image.shape.fillcolor = 'none'; /* Don't show blank white shapeangle when waiting for image to load. */
    el.vml.image.fill.type = 'tile'; /* Makes image show up. */
    el.vml.color.fill.on = false; /* Actually going to apply vml element's style.backgroundColor, so hide the whiteness. */
    lib.attachHandlers(el);
    lib.giveLayout(el);
    lib.giveLayout(el.offsetParent);
    el.vmlInitiated = true;
    lib.applyVML(el); /* Render! */
  }
};
try {
  document.execCommand("BackgroundImageCache", false, true); /* TredoSoft Multiple IE doesn't like this, so try{} it */
} catch(r) {}
DD_belatedPNG.createVmlNameSpace();
DD_belatedPNG.createVmlStyleSheet();